The authors report 63 cases of insertion of testicular prostheses (Lattimer model in Silastic, manufactured by Dow Corning) in patients who had undergone castration for testicular cancer. A study of the early and late post-operative complications, which were relatively rare and always benign, allows several simple rules to be proposed regarding this surgical procedure. There does not seem to be any problem with long term tolerance to medical silicones, after a ten year follow up period for the earliest cases. The insertion of an implant does not in any way delay continuation of treatment for testicular cancer.